// Copyright 2018 Prometheus Team
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package cli

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"time"

	kingpin "github.com/alecthomas/kingpin/v2"

	"github.com/prometheus/alertmanager/api/v2/client/silence"
	"github.com/prometheus/alertmanager/api/v2/models"
	"github.com/prometheus/alertmanager/cli/format"
	"github.com/prometheus/alertmanager/matchers/compat"
)

type silenceQueryCmd struct {
	expired   bool
	quiet     bool
	createdBy string
	ID        string
	matchers  []string
	within    time.Duration
}

const querySilenceHelp = `Query Alertmanager silences.

Amtool has a simplified prometheus query syntax, but contains robust support for
bash variable expansions. The non-option section of arguments constructs a list
of "Matcher Groups" that will be used to filter your query. The following
examples will attempt to show this behaviour in action:

amtool silence query alertname=foo node=bar

	This query will match all silences with the alertname=foo and node=bar label
	value pairs set.

amtool silence query foo node=bar

	If alertname is omitted and the first argument does not contain a '=' or a
	'=~' then it will be assumed to be the value of the alertname pair.

amtool silence query 'alertname=~foo.*'

	As well as direct equality, regex matching is also supported. The '=~' syntax
	(similar to prometheus) is used to represent a regex match. Regex matching
	can be used in combination with a direct match.

In addition to filtering by silence labels, one can also query for silences
that are due to expire soon with the "--within" parameter. In the event that
you want to preemptively act upon expiring silences by either fixing them or
extending them. For example:

amtool silence query --within 8h

returns all the silences due to expire within the next 8 hours. This syntax can
also be combined with the label based filtering above for more flexibility.

The "--expired" parameter returns only expired silences. Used in combination
with "--within=TIME", amtool returns the silences that expired within the
preceding duration.

amtool silence query --within 2h --expired

returns all silences that expired within the preceding 2 hours.
`

func configureSilenceQueryCmd(cc *kingpin.CmdClause) {
	var (
		c        = &silenceQueryCmd{}
		queryCmd = cc.Command("query", querySilenceHelp).Default()
	)

	queryCmd.Flag("expired", "Show expired silences instead of active").BoolVar(&c.expired)
	queryCmd.Flag("quiet", "Only show silence ids").Short('q').BoolVar(&c.quiet)
	queryCmd.Flag("created-by", "Show silences that belong to this creator").StringVar(&c.createdBy)
	queryCmd.Flag("id", "Get a single silence by its ID").StringVar(&c.ID)
	queryCmd.Arg("matcher-groups", "Query filter").StringsVar(&c.matchers)
	queryCmd.Flag("within", "Show silences that will expire or have expired within a duration").DurationVar(&c.within)
	queryCmd.Action(execWithTimeout(c.query))
}

func (c *silenceQueryCmd) query(ctx context.Context, _ *kingpin.ParseContext) error {
	if len(c.matchers) > 0 {
		// If the parser fails then we likely don't have a (=|=~|!=|!~) so lets
		// assume that the user wants alertname=<arg> and prepend `alertname=`
		// to the front.
		_, err := compat.Matcher(c.matchers[0], "cli")
		if err != nil {
			c.matchers[0] = fmt.Sprintf("alertname=%s", strconv.Quote(c.matchers[0]))
		}
	}

	silenceParams := silence.NewGetSilencesParams().WithContext(ctx).WithFilter(c.matchers)

	amclient := NewAlertmanagerClient(alertmanagerURL)

	getOk, err := amclient.Silence.GetSilences(silenceParams)
	if err != nil {
		return err
	}

	displaySilences := []models.GettableSilence{}
	for _, silence := range getOk.Payload {
		// skip expired silences if --expired is not set
		if !c.expired && time.Time(*silence.EndsAt).Before(time.Now()) {
			continue
		}
		// skip active silences if --expired is set
		if c.expired && time.Time(*silence.EndsAt).After(time.Now()) {
			continue
		}
		// skip active silences expiring after "--within"
		if !c.expired && int64(c.within) > 0 && time.Time(*silence.EndsAt).After(time.Now().UTC().Add(c.within)) {
			continue
		}
		// skip silences that expired before "--within"
		if c.expired && int64(c.within) > 0 && time.Time(*silence.EndsAt).Before(time.Now().UTC().Add(-c.within)) {
			continue
		}
		// Skip silences if the author doesn't match.
		if c.createdBy != "" && *silence.CreatedBy != c.createdBy {
			continue
		}
		// Skip silences if the ID doesn't match.
		if c.ID != "" && c.ID != *silence.ID {
			continue
		}

		displaySilences = append(displaySilences, *silence)
	}

	if c.quiet {
		for _, silence := range displaySilences {
			fmt.Println(*silence.ID)
		}
	} else {
		formatter, found := format.Formatters[output]
		if !found {
			return errors.New("unknown output formatter")
		}
		if err := formatter.FormatSilences(displaySilences); err != nil {
			return fmt.Errorf("error formatting silences: %w", err)
		}
	}
	return nil
}
